1st. do not use session_register when using super global $_SESSION. it will act quirky or explode on you.

2nd. make sure that <?php is the very first thing in the file. make sure there is nothing output to the browser before <?php is called.

3rd header calls cannot be made after you see anything on the browser. like the 2nd thing I mentioned.

4th. If you do need to make a header call for a redirection make sure you include the FULL url. i.e http://www.yourserver.com/somepage.html older versions of Netscape, Opera, IE, Mozilla require the FULL url or will not work.